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When invasive animal species brought from overseas become established in Japan, they have a negative impact on the ecosystem. It is important to recognize this threat and take appropriate measures.
The release into the wild of red swamp crayfish and red-eared slider turtles, which are popular as pets, is now prohibited. There is no problem with continuing to keep them at home or in captivity elsewhere, but those who keep them must abide by the new rules and treat the creatures properly.
A government ordinance has placed these two species in the newly established category of “designated invasive alien species with conditions.” Designated invasive alien species are usually subject to wide prohibitions against not only their release into wild, but also their import and sale, or even keeping them.
However, it is estimated that 5.4 million red swamp crayfish and 1.6 million red-eared sliders, also known as “midori-game” green turtles in Japanese, are already being kept in people’s homes. There was concern that a blanket ban on keeping these animals would lead to many owners releasing them secretly.
Considering the large numbers of the crayfish and turtles being kept at home and elsewhere, it is a pragmatic measure to introduce a new regulatory framework that allows the keeping of such creatures but prohibits their sale or their release into the wild.
Red swamp crayfish were introduced before World War II as feed for edible bullfrogs. Red-eared sliders were imported as pets beginning in the 1950s and sold at such outlets as street vendors. Both are native to North America, are highly fertile, and established themselves throughout Japan after being released into the wild.
As a result, small native fish and aquatic plants were devoured, and the ecosystem suffered. This is a threat that will change the landscape of areas around Japan’s rivers, lakes and ponds. It takes a great deal of effort to eradicate such species once they have bred in great numbers. The Environment Ministry’s response may have come too late.
The lifespan of a red swamp crayfish is estimated at 4 to 5 years. The lifespan of a red-eared slider is believed to be 20 to 40 years, and it can grow to nearly 30 centimeters in length. It is essential for owners to provide an appropriate environment to prevent them from escaping and to keep their pets responsibly for a long period of time.
If owners of such species become unable to keep them any longer, they must find new owners or put them down. Owners are expected to be determined to take care of their animals until the end.
Crayfish and turtles are sometimes kept at schools. Because they are so familiar to people, there may be little awareness that red-eared sliders and red swamp crayfish are invasive species.
Many children keep such species at home. Young people must be thoroughly informed of details of the new regulations through social media and other means.
Even if the new regulations curb the release of these species into wild, continued efforts are still necessary to eradicate those that have already been released in the past. In this regard, it is important that the central government, local governments and environmental groups work together.
